Filter Installation and Method for Operating One Such Filter Installation

ABSTRACT

The invention relates to a filter installation, especially a seawater filter installation, comprising at least one fluid line ( 18,20 ) for transporting a biological fluid, a filter device ( 54 ) which is mounted in said fluid line and comprises at least one filter element ( 22 ) in a filter housing ( 10 ), and means for biological decontamination. The fact that the means for biological decontamination contain active substances that can be introduced into the filter housing ( 10 ), such as inert gases or special metals, ensures that toxic impurities cannot enter and the active substances used are ecofriendly unlike chemically produced fungicides and herbicides. The invention also relates to a method for operating said filter installation.

The invention relates to a filter installation, in particular a seawater filter installation, with at least one fluid line, by means of which a biologically contaminated fluid can be transported, and a filter means which is interposed in this fluid line, and which has at least one filter element in a filter housing, and with agents for biological decontamination.

DE 20 2004 002 616 U1 discloses a generic water filter installation, a seawater filter installation in particular, comprising a water line as a fluid line and a filter means connected between two line sections of the fluid line, with individual filter elements which are provided with a filter surface located in the filter interior for filtering water, one line section forming a feed line to the filter means for the water to be cleaned and one line section forming a drain line for the filtered water. In the known solution feeding and draining of the filter means can be blocked relative to the water line with blocking means (valves), and the filter interior can be heated by a heating means with the blocking means blocked to a setpoint temperature of more than 50° C., preferably approximately 60±5° C. for decontamination of the filter surface, preferably the filter means being designed as a backflushing filter with a backflushing means for cleaning the filter surfaces in counterflow to the actual filtering direction.

Aboard ship, such as for example container ships, so-called ballast water is pumped on board in a particular harbor or underway in certain waters to be able to equalize missing ship's ballast and ballast equalization can be achieved while sailing for example by a decreasing amount of fuel by taking on new seawater ballast and/or pumping seawater between the individual ballast chambers to level the ship. When a new harbor is being approached and ballast water is being pumped out into the harbor basin to load the ship with new cargo, it cannot be precluded that living organisms taken aboard in the original harbor or underway will be discharged in the new port of call, so that in a type of biological tourism foreign organisms become settled in the biotopes, where they in fact do not belong, with the result that they can displace native species to their complete extinction; this can lead to a serious environmental situation. In addition to viruses, fungi, algae, protozoa, other microorganisms can also be transported at the same time in this way; however, tiny organisms can indeed also be transported at the same time, including mussels and the like.

With the known solution according to the German utility model this biological contamination is controlled by heating all the parts which are located in the filter interior of the filter means for a sufficient time interval to a high enough temperature, for example 60° C., in order in this way to kill algae, microorganisms and other tiny organisms. With the corresponding backflushing process then the killed organisms are returned immediately to the original water and are not delivered into foreign water after a forthcoming voyage. By preference the known solution calls for cleaning by means of superheated steam. As a result of the indicated high temperature and considering that salt water is heated, this decontamination is highly corrosive and leads to the corresponding corrosion damage, thus necessitating the use of expensive materials, such as duplex steels, titanium or the like. The known solution is biologically very compatible for the environment; in particular no toxic contaminants are formed; only temperature control for the heating means to be triggered and monitored is very complex and requires correspondingly trained operators.

It had already been suggested in the prior art that the microorganisms in the filter fabrics of a filter means be destroyed by oxidation technologies using UV radiation; but ozone, chlorine dioxide and other toxic contaminants are formed which contraindicate industrial use. The described devices in the prior art need not be limited to seawater applications, but can fundamentally always be used wherever problems occur with respect to bacterial and organic contaminants, as can occur for example in water filtering in industrial facilities, such as power plants.

On the basis of this prior art, therefore the object of the invention is to make available a filter installation and a method for its operation which, while retaining the advantages of known solutions, specifically to be able to ensure highly effective decontamination of biological materials, are further improved such that they are reliable even over long periods of use, without toxic by-products forming or without possible corrosion being promoted, effective, economical cleaning being guaranteed. This object is achieved by a filter installation with the features of claim 1 in its entirety and a method with the features of claim 9.

In that, as specified in the characterizing part of claim 1, the agents for biological contamination have active ingredients such as inert gases or special metals which can be placed in the filter housing, it is ensured that toxic impurities cannot occur and the active substances used, in contrast to chemically produced fungicides and herbicides, are environmentally compatible by their being found again directly in nature in this way without harmful intermediate decomposition products. The indicated active substances according to the invention are also chosen such that corrosion damage can be avoided and, especially when using special metals, on the one hand effective corrosion protection can build up, even if the metals themselves specifically kill the indicated living organisms, including plant material. With the inventive method according to claim 9, the appropriate use of the filter installation according to claim 1 is taught.

In one preferred embodiment of the filter installation according to the invention, the inert gas is nitrogen gas which can be taken from at least one storage bottle, and which preferably after completion of the actual filtration can be flushed into the interior of the filter housing with the respective filter element. The inert gas nitrogen within the filter housing creates a dry, oxygen-free environment which is used to kill living organisms. This nitrogen gas can be very easily managed using devices; it is easily economically available worldwide as a refill gas and effectively controls the danger of corrosion. Instead of nitrogen gas, the filter means could optionally also be flushed in a less desirable version with compressed air; since compressed air is generally available aboard ship, its use however does not lead to an oxygen-free environment and thus it can be used only as an emergency measure. Preferably the inert gas in the associatable storage bottle is provided with high pressure such that the filter housing can also be flushed empty if the filter housing is still filled with seawater of a definable pressure (ambient pressure).

In another preferred embodiment of the filter installation according to the invention, in the filter housing copper is used as the special metal in the form of at least one sacrificial anode. Since copper occurs in the environment and is not environmentally harmful at a correspondingly high dilution by seawater, it is especially well suited for the indicated use, especially with respect to killing of the indicated living microorganisms. Due to the configuration as a sacrificial anode the copper removal in this respect also counteracts the continually prevailing corrosion. In an especially space-saving manner the sacrificial anode can be accommodated in the respective filter housing if it is part of the filter elements used. By integrating the copper sacrificial anode into the associatable filter elements moreover the fluid flow behavior within the filter housing is not hindered. This benefits overall operation of the system in terms of energy.

In one especially preferred embodiment of the filter installation according to the invention, it is moreover designed such that it ensures ordinary filtering operation on the one hand and on the other preferably at the same time allows backflushing for some of the filter elements in order in this way to be able to use the cleaned filter elements for new filtration operation. Preferably provision is furthermore made such that the fluid outlet of the filter means is provided with a triggerable check valve, in the fluid flow direction following in the fluid line a non-return valve being used such that in the opened position the exterior is connected to the associatable fluid line. As a result of the fluid lines which are very long in ships and power plants, water hammers can be avoided with the check valve blocked by the ambient air being able to flow after into the fluid lines via the non-return valve. Air volumes which may form in this way in the fluid line can be used then in the opposite direction as a damping element if water hammers in operation of the system can be expected in the opposite direction.

In the method according to the invention for operation of the filter installation as described above, coarse contaminants are filtered out of biologically contaminated fluid which has been supplied via a fluid line by means of the respective filter element in the filter housing of a filter means, agents for biological decontamination of the fluid releasing active substances such as inert gases and/or metal. The filter installation according to the invention can be operated as a seawater filter installation, but can also be used for water filtration in industrial facilities, such as power plants. Furthermore, applications are possible particularly when problems arise within fluids with bacterial and/or organic impurities.

The configuration according to the invention as shown in the drawings will be detailed below.

The single FIGURE shows, schematically and not to scale, partially in a section, partially in a perspective view, a side view of one embodiment of the filter installation according to the invention.

The filter installation shown in the FIGURE is designed as a backflushing device and has a cylindrical filter housing 10 with two sealing covers 12, 14 which can be attached to the filter housing 10 by way of flange connections 16. The filter housing 10 of the backflushing filter device has one filter inlet 18 for the fluid which is to be filtered and also one filter outlet 20 for the filtered fluid. Both the filter inlet 18 and also the filter outlet 20 are parts of a fluid line which is not detailed and which can run over very long distances, for example in the cargo space of a container ship (not shown). The fluid direction in filter operation is symbolized in the FIGURE with the corresponding arrows 21 at the filter inlet 18 and at the filter outlet 20.

Filter elements 22 which taper towards the top are inserted into the filter device, and also at least partially cylindrical filter elements (not shown) can replace the conical filter elements 22. The indicated conical filter elements 22 are preferably made as so-called tubular, wedge wire screen filter elements and are configured at distances from one another along a cylindrical (concentric) arc within the filter housing 10. For an embodiment which is not detailed, the filter elements 22 can be configured divided repeatedly into groups along cylindrical arcs. Conical filter elements have the advantage that they allow uniform through-flow, with the result of low pressure loss, and enable complete cleaning of the elements in the backflushing cycle.

The filter elements 22 shown in the FIGURE discharge with their inlet cross section 24, that is, with their free openings, into recesses of the lower sealing cover 14 which are made correspondingly cylindrical. On their respective other end which is opposite, the filter elements 22 being used are provided with sealing caps 26 via which the filter elements 22 are held on a plate-shaped intermediate piece 28 which is abutted by the upper sealing cover 12 from the top.

For actual backflushing with the backflushing filter device, there is a drivable flushing arm 30 which on its underside provides for a connection in the form of a fluid outlet 32 for fouled fluid. The flushing arm 30 can be moved via a drive rod 34 in succession to under the inlet cross sections 24 of the filter elements 22. Backflushing therefore takes place continuously with the actual filtration process, only the filter elements 22 being backflushed, from the outside to the inside, with the cleaned, filtered fluid which forms in filtration with the other filter elements 22, the flushing arm 30 extending in succession under the free inlet cross sections 24 of the filter elements. The backflushing direction is indicated in the FIGURE with arrows 35 from the outside to the inside and the conventional filtration direction analogously with arrows 35 a, this time from the inside to the outside. If the filter elements 22 which are grouped along cylindrical or concentric arcs are configured repeatedly within the filter housing 10, the flushing arm 30 requires another arm section of different length (not shown), which can then extend under the other group of filter elements 22 on the side of their respective inlet cross section 24.

The discharge of the fluid which has been fouled in this way and which forms during backflushing proceeds via the tubular fluid outlet 32. The indicated drive housing 34 extends through the filter housing 10 along the longitudinal axis 36 of the backflushing device and both through the upper sealing cover 12 and also the lower sealing cover 14. For driving of the drive rod 34, especially in the form of a hollow shaft, on the upper sealing cover 12 there is a spline shaft connection which is not detailed and via which the drive rod 34 can be driven with an electric motor 38 to rotate around the longitudinal axis 36. The filter inlet 18 is formed in terms of its outside wall in the form of a diffusor which reduces the fluid inlet speed of the fouled fluid which is to be filtered with a simultaneous pressure increase on the inlet cross sections 24 of the conical elements 22 which are left open by the flushing arm 30. The diffusor action is promoted especially by the inlet cross sections at the filter inlet 18 and also the cross section of the receiving space 40 being made essentially the same and the transition between the filter inlet 18 and the receiving space 40 taking place essentially uniformly, without a reduction in cross section.

The conical structure of the filter elements 22 results in that the passage surface in the respective element is very large, the distance between the conical elements 22 increasing in the direction of the filter outlet 20 so that a smaller resistance is offered to the filtered fluid upon emergence from the interior of the respective filter element 22, compared to known solutions with exclusively cylindrical elements. Furthermore, the conical structure of the filter elements 32 yields a constant liquid flow when the elements are being backflushed. The fluid outlet 32 can be blocked by means of a controllable check valve 42, following in the fluid flow direction in another fluid line 44 a spring-loaded non-return valve 46 acting with a closing ball which points toward the exterior 48 and being held spring-loaded in this way in the closed position. If the check valve 42 is closed and a type of water hammer situation occurs due to the other fluid line 44 which is made long, the spring-loaded non-return valve 46 can open and in this way can produce an air-guiding connection between the exterior 48 and the interior of the fluid line 44. In this way the check valve 42 is relieved of replenishing processes within the other fluid line 44. In the reverse case, that is, for fluid pressure loading in the direction of the check valve 42, the non-return valve 46 effects a spring-loaded closure of the connection between the exterior 48 and the fluid line 44 and the air volume enclosed for example in the fluid line 44 forms a type of damper element which likewise relieves the check valve 42 in the closed state and subsequent system parts of the filter means against water hammers. Preferably the filter installation can be mounted upright by way of base legs 50 above the floor of the hall or deck of the ship 52.

The filter means designated as a whole as 54 in the FIGURE can be connected to a storage bottle 56 which can likewise be mounted upright above the floor or deck 52 and which preferably holds nitrogen gas as the inert gas under high pressure. Via a pressure reducer 58 and via a solenoid valve 60 which can be triggered from the outside, in this way the interior of the storage bottle 56 can be connected via a connecting line 62 to the filter means 54 by one free end of the connecting line 62 extending through the sealing cover 12 and thus establishing a connection to the interior of the filter housing 10. Furthermore, provision is made such that at least for some of the filter elements 22 a type of sacrificial anode 64 made as a copper rod runs in their interior and in their longitudinal direction. This sacrificial anode 64 is preferably made as a solid rod and is connected via a screw connection, which is not detailed, to the upper sealing cap 26 of the associatable filter elements 22. By permanent release of copper the sacrificial anode 64 is used up so that from time to time a new sacrificial anode 64 must be installed; this can optionally take place with replacement of a used filter element 22 as a whole.

For the sake of better understanding, the filter installation will be detailed below using a seawater application. After opening the corresponding sea valves which are not detailed on the ship's hull, seawater, generally fouled harbor water, penetrates via the filter inlet 18 in the filter means 54 and the individual filter elements 22 in the direction 35 a of the arrow clean the fouled harbor water, and the cleaned seawater can be supplied in the direction 21 of the arrow via the filter outlet 20 to ballast tanks in the ship's hull which are not detailed. At the same time, the seawater which has been cleaned in this way is used simultaneously to clean the fouled filter elements 22 during filtration operation in the opposite direction according to the direction 35 of the arrow and this fouled liquid travels back to the exterior via the other fluid line 44 with the check valve 44 opened and the sea valves opened accordingly. In this conventional filtration operation, it cannot be precluded that the filter elements 22 become at least partially clogged with biological material such as microorganisms, their having ideal growth conditions especially in voyages in warm waters, in order to spread further within the filter means 54. If then the filter means 54 were restarted in other waters, that is, in a foreign harbor or on the open sea, this would lead to the biologically entrained material being flushed out with the result that the indicated microorganisms could then penetrate into the foreign biotope.

To prevent this, according to the invention, still in the original harbor or at sites of conventional seawater filtration operation, the filter means 54 as such is shut down and after opening the solenoid valve 60 nitrogen gas from the storage bottle 56 penetrates via the pressure reduction valve 58 into the interior of the filter housing 10. Residual seawater fluid which may remain in the filter housing 10 is displaced by the high nitrogen pressure out of the interior of the filter housing 10 so that the filter elements 22 held in the filter housing 10 are completely flushed by the nitrogen gas. Thus, within the filter housing 10 an extremely dry, oxygen-free environment is created; this kills microorganisms, also in the form of plant material, which may have entered. If then the filter installation is restarted elsewhere, there is no danger of unintentional discharge of foreign organisms. In addition to or instead of inert gas supply, the sacrificial anode 64 can also be used as the active substance; it is composed preferably of a metal material which is toxic, especially fatal to microorganisms. It has been shown that especially with respect to the desired corrosion protection, sacrificial anodes 64 of copper can be advantageously used.

With the solution according to the invention, not only is a filter installation created, with which conventional filtration tasks for elimination of contamination, especially in seawater, can be performed, but with which it is also possible to kill biological material with a simultaneous increase of corrosion protection. The filter installation according to the invention manages with few standard components, so that the cost for implementing the filter installation is reduced and furthermore reliable use takes place due to the standard components. The filter installation can be used wherever fluid media must be filtered and wherever microbial burdens which are not desirable can be expected. 

1. Filter installation, in particular a seawater filter installation, with at least one fluid line (18, 20), by means of which a biologically contaminated fluid can be transported, and a filter means (54) which is interposed in this fluid line, and which has at least one filter element (22) in a filter housing (10), and with agents for biological decontamination, characterized in that the agents for biological contamination have active ingredients such as inert gases or special metals which can be placed in the filter housing (10).
 2. The filter installation according to claim 1, wherein the inert gas is nitrogen gas which can be taken from at least one storage bottle (56) and after completion of filtration flushes the interior of the filter housing (10) with the respective filter element (22).
 3. The filter installation according to claim 2, wherein the inert gas in the storage bottle (56) is provided with such a high pressure that the filter housing (10) is flushed empty during decontamination.
 4. The filter installation according to claim 1, wherein copper is used as the special metal which is located in the filter housing (10) in the form of at least one sacrificial anode (64).
 5. The filter installation according to claim 4, wherein at least for some of the filter elements (22) used they accommodate the respective sacrificial anode (64).
 6. The filter installation according to claim 1, wherein the filter means (54) has individual filter elements (22) configured in at least one concentric path and which are interchangeably accommodated in the filter housing (10) which has one filter inlet (18) for the biologically contaminated fluid which is to be filtered and one filter outlet (20) for the filtered fluid, wherein flow is possible through the filter elements (22) for filtration or backflushing in both directions, wherein at the same time some filter elements (22) undertake filtration and at least one other filter element (22) can be backflushed for cleaning its effective filter surface, and wherein for backflushing there is a drivable flushing arm (30) which has one fluid outlet (32) for fouled fluid and which can be moved in succession to under the free inlet cross sections (24) of the filter elements (22).
 7. The filter installation according to claim 6, wherein the fluid outlet (32) has a triggerable check valve (42) and following in the fluid flow direction located in another fluid line (44) has a non-return valve (46) which in the opened position connects the exterior (48) to the other fluid line (44).
 8. The filter installation according to claim 1, wherein at least some of the filter elements (22) are made conical.
 9. Method for operation of a filter installation according to claim 1, wherein biologically contaminated fluid supplied via one fluid line (18, 20) is filtered by means of the respective filter element (22) in the filter housing (10) of a filter means (44) and wherein agents for biological decontamination of the fluid release active substances such as inert gases and/or metals. 